New to Serial Communication. Help?

Hello, Don't know if its the right place to post this or not... so i have never worked on serial comm.. just know the theoretical difference between serial and parallel comm.. but very keen to start learning serial comm now, so help me in its start.. What to study for beginning it... BASICS.....?????????????

The basics is that

Serial Parallel
Send the bits of the number/characters one bit at a time Send all the bits simultaenously.
Requires only one wire (plus ground) Requires at least as many wires as you want to send bits
More wires used for clock and flow control in some systems Also may use some extra wires for flow, clock, reset
. Several "Parallel words" will then be sent serially
RS232, SATA, Arduino TX/RX, USB, Ethernet LPT interface, IDE-disk interface

(edit added a bit about multiple parallel words)

Serial just means that only one side can talk at a time. Parallel means that both sides can talk at the same time.

Thanks alot, i studied and got some start in my mind... so i'm happy with that.. Now i wan't to implement it physically :wink:
But i wan't to ask that what stuff (available easily and cheaply) can have serial comm so i can practice with that???

by the way, i have “serial data cable” of my simple nokia old model mobile, i just cut that cable from the side connected to mobile, and left the other side that can be connected to serial port of PC, so from mobile side of cable i got 3 wires, i think they may be RX,TX and ground?? thats what i think :roll_eyes:
So my question is this that can i connect that cable b/w PC and my arduino RX/TX and ground?? What data i can transfer serially???

"Serial just means that only one side can talk at a time. Parallel means that both sides can talk at the same time."
That sounds more like a comparison of half-duplex vs full-duplex.

"the other side that can be connected to serial port of PC, so from mobile side of cable i got 3 wires, i think they may be RX,TX and ground?? "
The cable plugs into a 9-pin D-shaped connector on the PC?
If so, that is RS232 output. The voltage on the Rx/Tx pins will swing from +/-3V up to maybe +/- 15V.
You need an RS232 adapter so it can talk the arduino's D0/D1 pins and not damage anything.

You can get a couple of transistors and wire it up like the input section of this Serial Arduino
http://webzone.k3.mah.se/k3dacu/arduino/releases/serial_v2/arduino_rs232_v2.png

Then you can download sketches into your arduino, and use the IDE Serial Monitor to debug your sketches, or provide user interfacing.

PaulS:
Serial just means that only one side can talk at a time. Parallel means that both sides can talk at the same time.

Oh? On what basis?

Two-wire serial (data + Gnd) will be one-way. Three-wire serial (Tx + Rx + Gnd) will be two-way.

Parallel was often one-way (eg. printers). I think at the least you would need 11 wires (8 data bits + Gnd + Clock + Acknowledge) unless you are sending 4-bit data like some LCD screens seem to.

I suppose parallel can be two-way if you include a R/W line (i.e. which "way" is active). But then you could conceivably do that as well with serial. But of course there is hardly any point as the extra wire may as well be the "other way".


It's interesting that parallel and serial are both still alive. Some LCD screens I have bought use parallel comms (either 4 or 8 bit) to send their data. That is nice and simple. Others use I2C, Async Serial, or SPI, all of which are forms of serial comms.

Parallel is arguably faster, but I think is limited by crosstalk between the data bits. Modern serial (eg. USB2) can achieve very high speeds.

Regarding the RS-232 vs "serial" question... there's more at....

(Notes on the electronics you need are there, among other things)

Also note an unkind "gotcha": In RS-232, a low voltage stands for "1", and a high voltage for "0". May not matter, depending on the level you are working at, but can be a major pain if you aren't aware.

The cable plugs into a 9-pin D-shaped connector on the PC?
If so, that is RS232 output.

yes that is RS232

The voltage on the Rx/Tx pins will swing from +/-3V up to maybe +/- 15V.
You need an RS232 adapter so it can talk the arduino's D0/D1 pins and not damage anything.

RS232 adapter???
u mean regulator for RS232???

Also note an unkind "gotcha": In RS-232, a low voltage stands for "1", and a high voltage for "0". May not matter, depending on the level you are working at, but can be a major pain if you aren't aware.

oh if thats the case so it can create problems sometime if someone don't know..
thanks tkbyd..

tkbyd:
Also note an unkind "gotcha": In RS-232, a low voltage stands for "1", and a high voltage for "0". May not matter, depending on the level you are working at, but can be a major pain if you aren't aware.

Another word of warning. From the quoted page:

A bunch of engineers met and produced a document, and it says, among other things, that in any "RS-232" data stream, "1" is represented by a negative voltage between -3 and -15 volts.

So a 1 is not just a zero voltage, it is a negative voltage, so you need to have a suitable buffer/conversion chip to handle that.

RS232 adapter???
u mean regulator for RS232???

No, I mean an RS232 adapter like I posted a link to. NPN, PNP transistor, couple of resistors, couple diodes, and a capacitor.
http://webzone.k3.mah.se/k3dacu/arduino/releases/serial_v2/arduino_rs232_v2.png
This brings the +/- levels to 0/5V to interface with D0/D1 without breaking anything (or using newsoftserial on other pins).

This will let you have comm’s with your arduino per your goal : “what stuff (available easily and cheaply)”
Or let your arduino talk to other devices.

oops NICK.. these points making me curious about the safety of my board :~

CrossRoads:
http://webzone.k3.mah.se/k3dacu/arduino/releases/serial_v2/arduino_rs232_v2.png

This brings the +/- levels to 0/5V to interface with D0/D1 without breaking anything (or using newsoftserial on other pins).

hmmm.. if it can bring it on level (0 to 5V) so then board will be safe but i can't try this now bcuz i don't have all the stuff at home, and radio shack is far away, will try next week or next-next week.. i hope it will work..